Carrier configuration in a wireless device, base station, and network

ABSTRACT

A base station transmits radio resource control message(s) to a wireless device configuring second carrier(s). Each of the second carrier(s) is assigned to a carrier group in a plurality of carrier groups comprising a first carrier group and at least one second carrier group. The control message(s) comprise parameters. If parameters comprise a carrier group index for the second carrier, the wireless device assigns the second carrier to one of the at least one second carrier group identified by the carrier group index. Otherwise, the wireless device assigns the second carrier to the first carrier group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/556,165,filed Jul. 23, 2012, now U.S. Pat. No. 8,395,985, entitled “TimeAlignment in Multicarrier OFDM Network,” which claims the benefit ofU.S. Provisional Application No. 61/511,544, filed Jul. 25, 2011,entitled “Time Alignment in Multicarrier OFDM Network,” and U.S.Provisional Application No. 61/528,226, filed Aug. 27, 2011, entitled“Carrier Configuration in Multicarrier Systems,” and U.S. ProvisionalApplication No. 61/556,045, filed Nov. 4, 2011, entitled “MultipleTiming Advances in Multicarrier Systems,” which are hereby incorporatedby reference in its entirety.

This application is related to Non-Provisional application Ser. No.13/556,317, filed Jul. 24, 2012, now U.S. Pat. No. 8,391,129, entitled“Time Alignment in Multicarrier Systems.”

BACKGROUND OF THE INVENTION

Example embodiments of the present invention enhance time alignment in amulticarrier OFDM communication system. Embodiments of the technologydisclosed herein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to enhancing time alignment in amulticarrier OFDM communication system employing multiple timingadvances.

FIG. 5 is a block diagram depicting a system 500 for transmitting datatraffic generated by a wireless device 502 to a server 508 over amulticarrier OFDM radio according to one aspect of the illustrativeembodiments. The system 500 may include a Wireless CellularNetwork/Internet Network 507, which may function to provide connectivitybetween one or more wireless devices 502 (e.g., a cell phone, PDA(personal digital assistant), other wirelessly-equipped device, and/orthe like), one or more servers 508 (e.g. multimedia server, applicationservers, email servers, or database servers) and/or the like.

As shown, the access network may include a plurality of base stations503 . . . 504. Base station 503 . . . 504 of the access network mayfunction to transmit and receive RF (radio frequency) radiation 505 . .. 506 at one or more carrier frequencies, and the RF radiation mayprovide one or more air interfaces over which the wireless device 502may communicate with the base stations 503 . . . 504. The user 501 mayuse the wireless device (or UE: user equipment) to receive data traffic,such as one or more multimedia files, data files, pictures, video files,or voice mails, etc. The wireless device 502 may include applicationssuch as web email, email applications, upload and ftp applications, MMS(multimedia messaging system) applications, or file sharingapplications. In another example embodiment, the wireless device 502 mayautomatically send traffic to a server 508 without direct involvement ofa user. For example, consider a wireless camera with automatic uploadfeature, or a video camera uploading videos to the remote server 508, ora personal computer equipped with an application transmitting traffic toa remote server.

Some example embodiments of the technology disclosed enhances timealignment in a multicarrier OFDM communication system employing multipletiming advances.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present inventionare described herein with reference to the drawings, in which:

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention;

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention;

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention;

FIG. 4 is a block diagram of a base station and a wireless device as peran aspect of an embodiment of the present invention;

FIG. 5 is a block diagram depicting a system for transmitting datatraffic over an OFDM radio system as per an aspect of an embodiment ofthe present invention;

FIG. 6 illustrates the subframe timing as per an aspect of an embodimentof the present invention;

FIG. 7 depicts message flows between a base station and a wirelessdevice as per an aspect of an embodiment of the present invention;

FIG. 8 depicts an example flow chart for a time alignment process in awireless device as per an aspect of an embodiment of the presentinvention;

FIG. 9 depicts an example flow chart for a time alignment process in abase station as per an aspect of an embodiment of the present invention;and

FIG. 10 depicts an example flow chart for a time alignment process in awireless device as per an aspect of an embodiment of the presentinvention.

BRIEF SUMMARY OF THE INVENTION

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one radio resource control message from abase station. The at least one radio resource control message may causeconfiguration of a plurality of carriers comprising a first carrier andat least one second carrier. The at least one radio resource controlmessage may comprise a carrier group index for a second carrier in theat least one second carrier. The carrier group index may identify asecond carrier group. The second carrier group may be one of a pluralityof carrier groups. The second carrier group may comprise a second subsetof the at least one second carrier. The wireless device may receive fromthe base station, a control command. The control command may cause thewireless device to transmit a random access preamble on the seconduplink carrier. The control command may comprise a preamble indexcorresponding to the random access preamble. The wireless device maytransmit the random access preamble. Transmission timing of the randomaccess preamble may be determined, at least in part, by employing asynchronization signal transmitted on one of at least one downlinkcarrier in the second carrier group.

According to some of the various aspects of embodiments, a base stationmay transmit at least one radio resource control message to a wirelessdevice. The at least one radio resource control message may beconfigured to cause configuration of a plurality of carriers comprisinga first carrier and at least one second carrier. The at least one radioresource control message may comprise a carrier group index for a secondcarrier in the at least one second carrier. The carrier group index mayidentify a second carrier group. The second carrier group may be one ofa plurality of carrier groups. The second carrier group may comprise asecond subset of the at least one second carrier. The base station maytransmit to the wireless device a control command. The control commandmay be configured to cause the wireless device to transmit a randomaccess preamble on the second uplink carrier. The control command maycomprise a preamble index corresponding to the random access preamble.The base station may receive the random access preamble. Transmissiontiming of the random access preamble may be determined, at least inpart, by employing a synchronization signal transmitted on one of atleast one downlink carrier in the second carrier group.

DETAILED DESCRIPTION OF EMBODIMENTS

Example embodiments of the present invention enhance time alignment in amulticarrier OFDM communication system. Embodiments of the technologydisclosed herein may be employed in the technical field of multicarriercommunication systems. More particularly, the embodiments of thetechnology disclosed herein may relate to enhancing time alignment in amulticarrier OFDM communication system employing multiple timingadvances.

Example embodiments of the invention may be implemented using variousphysical layer modulation and transmission mechanisms. Exampletransmission mechanisms may include, but are not limited to: CDMA (codedivision multiple access), OFDM (orthogonal frequency divisionmultiplexing), TDMA (time division multiple access), Wavelettechnologies, and/or the like. Hybrid transmission mechanisms such asTDMA/CDMA, and OFDM/CDMA may also be employed. Various modulationschemes may be applied for signal transmission in the physical layer.Examples of modulation schemes include, but are not limited to: phase,amplitude, code, a combination of these, and/or the like. An exampleradio transmission method may implement QAM (quadrature amplitudemodulation) using BPSK (binary phase shift keying), QPSK (quadraturephase shift keying), 16-QAM, 64-QAM, 256-QAM, and/or the like. Physicalradio transmission may be enhanced by dynamically or semi-dynamicallychanging the modulation and coding scheme depending on transmissionrequirements and radio conditions.

FIG. 1 is a diagram depicting example sets of OFDM subcarriers as per anaspect of an embodiment of the present invention. As illustrated in thisexample, arrow(s) in the diagram may depict a subcarrier in amulticarrier OFDM system. The OFDM system may use technology such asOFDM technology, SC-OFDM (single carrier-OFDM) technology, or the like.For example, arrow 101 shows a subcarrier transmitting informationsymbols. FIG. 1 is for illustration purposes, and a typical multicarrierOFDM system may include more subcarriers in a carrier. For example, thenumber of subcarriers in a carrier may be in the range of 10 to 10,000subcarriers. FIG. 1 shows two guard bands 106 and 107 in a transmissionband. As illustrated in FIG. 1, guard band 106 is between subcarriers103 and subcarriers 104. The example set of subcarriers A 102 includessubcarriers 103 and subcarriers 104. FIG. 1 also illustrates an exampleset of subcarriers B 105. As illustrated, there is no guard band betweenany two subcarriers in the example set of subcarriers B 105. Carriers ina multicarrier OFDM communication system may be contiguous carriers,non-contiguous carriers, or a combination of both contiguous andnon-contiguous carriers.

FIG. 2 is a diagram depicting an example transmission time and receptiontime for two carriers as per an aspect of an embodiment of the presentinvention. A multicarrier OFDM communication system may include one ormore carriers, for example, ranging from 1 to 10 carriers. Carrier A 204and carrier B 205 may have the same or different timing structures.Although FIG. 2 shows two synchronized carriers, carrier A 204 andcarrier B 205 may or may not be synchronized with each other. Differentradio frame structures may be supported for FDD (frequency divisionduplex) and TDD (time division duplex) duplex mechanisms. FIG. 2 showsan example FDD frame timing. Downlink and uplink transmissions may beorganized into radio frames 201. In this example, radio frame durationis 10 msec. Other frame durations, for example, in the range of 1 to 100msec may also be supported. In this example, each 10 ms radio frame 201may be divided into ten equally sized sub-frames 202. Other subframedurations such as including 0.5 msec, 1 msec, 2 msec, and 5 msec mayalso be supported. Sub-frame(s) may consist of two or more slots 206.For the example of FDD, 10 subframes may be available for downlinktransmission and 10 subframes may be available for uplink transmissionsin each 10 ms interval. Uplink and downlink transmissions may beseparated in the frequency domain. Slot(s) may include a plurality ofOFDM symbols 203. The number of OFDM symbols 203 in a slot 206 maydepend on the cyclic prefix length and subcarrier spacing.

In an example case of TDD, uplink and downlink transmissions may beseparated in the time domain. According to some of the various aspectsof embodiments, each 10 ms radio frame may include two half-frames of 5ms each. Half-frame(s) may include eight slots of length 0.5 ms andthree special fields: DwPTS (Downlink Pilot Time Slot), GP (GuardPeriod) and UpPTS (Uplink Pilot Time Slot). The length of DwPTS andUpPTS may be configurable subject to the total length of DwPTS, GP andUpPTS being equal to 1 ms. Both 5 ms and 10 ms switch-point periodicitymay be supported. In an example, subframe 1 in all configurations andsubframe 6 in configurations with 5 ms switch-point periodicity mayinclude DwPTS, GP and UpPTS. Subframe 6 in configurations with 10 msswitch-point periodicity may include DwPTS. Other subframes may includetwo equally sized slots. For this TDD example, GP may be employed fordownlink to uplink transition. Other subframes/fields may be assignedfor either downlink or uplink transmission. Other frame structures inaddition to the above two frame structures may also be supported, forexample in one example embodiment the frame duration may be selecteddynamically based on the packet sizes.

FIG. 3 is a diagram depicting OFDM radio resources as per an aspect ofan embodiment of the present invention. The resource grid structure intime 304 and frequency 305 is illustrated in FIG. 3. The quantity ofdownlink subcarriers or resource blocks (RB) (in this example 6 to 100RBs) may depend, at least in part, on the downlink transmissionbandwidth 306 configured in the cell. The smallest radio resource unitmay be called a resource element (e.g. 301). Resource elements may begrouped into resource blocks (e.g. 302). Resource blocks may be groupedinto larger radio resources called Resource Block Groups (RBG) (e.g.303). The transmitted signal in slot 206 may be described by one orseveral resource grids of a plurality of subcarriers and a plurality ofOFDM symbols. Resource blocks may be used to describe the mapping ofcertain physical channels to resource elements. Other pre-definedgroupings of physical resource elements may be implemented in the systemdepending on the radio technology. For example, 24 subcarriers may begrouped as a radio block for a duration of 5 msec.

Physical and virtual resource blocks may be defined. A physical resourceblock may be defined as N consecutive OFDM symbols in the time domainand M consecutive subcarriers in the frequency domain, wherein M and Nare integers. A physical resource block may include M×N resourceelements. In an illustrative example, a resource block may correspond toone slot in the time domain and 180 kHz in the frequency domain (for 15KHz subcarrier bandwidth and 12 subcarriers). A virtual resource blockmay be of the same size as a physical resource block. Various types ofvirtual resource blocks may be defined (e.g. virtual resource blocks oflocalized type and virtual resource blocks of distributed type). Forvarious types of virtual resource blocks, a pair of virtual resourceblocks over two slots in a subframe may be assigned together by a singlevirtual resource block number. Virtual resource blocks of localized typemay be mapped directly to physical resource blocks such that sequentialvirtual resource block k corresponds to physical resource block k.Alternatively, virtual resource blocks of distributed type may be mappedto physical resource blocks according to a predefined table or apredefined formula. Various configurations for radio resources may besupported under an OFDM framework, for example, a resource block may bedefined as including the subcarriers in the entire band for an allocatedtime duration.

According to some of the various aspects of embodiments, an antenna portmay be defined such that the channel over which a symbol on the antennaport is conveyed may be inferred from the channel over which anothersymbol on the same antenna port is conveyed. In some embodiments, theremay be one resource grid per antenna port. The set of antenna port(s)supported may depend on the reference signal configuration in the cell.Cell-specific reference signals may support a configuration of one, two,or four antenna port(s) and may be transmitted on antenna port(s) {0},{0, 1}, and {0, 1, 2, 3}, respectively. Multicast-broadcast referencesignals may be transmitted on antenna port 4. Wireless device-specificreference signals may be transmitted on antenna port(s) 5, 7, 8, or oneor several of ports {7, 8, 9, 10, 11, 12, 13, 14}. Positioning referencesignals may be transmitted on antenna port 6. Channel state information(CSI) reference signals may support a configuration of one, two, four oreight antenna port(s) and may be transmitted on antenna port(s) 15, {15,16}, {15, . . . , 18} and {15, . . . , 22}, respectively. Variousconfigurations for antenna configuration may be supported depending onthe number of antennas and the capability of the wireless devices andwireless base stations.

According to some embodiments, a radio resource framework using OFDMtechnology may be employed. Alternative embodiments may be implementedemploying other radio technologies. Example transmission mechanismsinclude, but are not limited to: CDMA, OFDM, TDMA, Wavelet technologies,and/or the like. Hybrid transmission mechanisms such as TDMA/CDMA, andOFDM/CDMA may also be employed.

FIG. 4 is an example block diagram of a base station 401 and a wirelessdevice 406, as per an aspect of an embodiment of the present invention.A communication network 400 may include at least one base station 401and at least one wireless device 406. The base station 401 may includeat least one communication interface 402, at least one processor 403,and at least one set of program code instructions 405 stored innon-transitory memory 404 and executable by the at least one processor403. The wireless device 406 may include at least one communicationinterface 407, at least one processor 408, and at least one set ofprogram code instructions 410 stored in non-transitory memory 409 andexecutable by the at least one processor 408. Communication interface402 in base station 401 may be configured to engage in communicationwith communication interface 407 in wireless device 406 via acommunication path that includes at least one wireless link 411.Wireless link 411 may be a bi-directional link. Communication interface407 in wireless device 406 may also be configured to engage in acommunication with communication interface 402 in base station 401. Basestation 401 and wireless device 406 may be configured to send andreceive data over wireless link 411 using multiple frequency carriers.According to some of the various aspects of embodiments, transceiver(s)may be employed. A transceiver is a device that includes both atransmitter and receiver. Transceivers may be employed in devices suchas wireless devices, base stations, relay nodes, and/or the like.Example embodiments for radio technology implemented in communicationinterface 402, 407 and wireless link 411 are illustrated are FIG. 1,FIG. 2, and FIG. 3. and associated text.

FIG. 5 is a block diagram depicting a system 500 for transmitting datatraffic generated by a wireless device 502 to a server 508 over amulticarrier OFDM radio according to one aspect of the illustrativeembodiments. The system 500 may include a Wireless CellularNetwork/Internet Network 507, which may function to provide connectivitybetween one or more wireless devices 502 (e.g., a cell phone, PDA(personal digital assistant), other wirelessly-equipped device, and/orthe like), one or more servers 508 (e.g. multimedia server, applicationservers, email servers, or database servers) and/or the like.

It should be understood, however, that this and other arrangementsdescribed herein are set forth for purposes of example only. As such,those skilled in the art will appreciate that other arrangements andother elements (e.g., machines, interfaces, functions, orders offunctions, etc.) may be used instead, some elements may be added, andsome elements may be omitted altogether. Further, as in mosttelecommunications applications, those skilled in the art willappreciate that many of the elements described herein are functionalentities that may be implemented as discrete or distributed componentsor in conjunction with other components, and in any suitable combinationand location. Still further, various functions described herein as beingperformed by one or more entities may be carried out by hardware,firmware and/or software logic in combination with hardware. Forinstance, various functions may be carried out by a processor executinga set of machine language instructions stored in memory.

As shown, the access network may include a plurality of base stations503 . . . 504. Base station 503 . . . 504 of the access network mayfunction to transmit and receive RF (radio frequency) radiation 505 . .. 506 at one or more carrier frequencies, and the RF radiation mayprovide one or more air interfaces over which the wireless device 502may communicate with the base stations 503 . . . 504. The user 501 mayuse the wireless device (or UE: user equipment) to receive data traffic,such as one or more multimedia files, data files, pictures, video files,or voice mails, etc. The wireless device 502 may include applicationssuch as web email, email applications, upload and ftp applications, MMS(multimedia messaging system) applications, or file sharingapplications. In another example embodiment, the wireless device 502 mayautomatically send traffic to a server 508 without direct involvement ofa user. For example, consider a wireless camera with automatic uploadfeature, or a video camera uploading videos to the remote server 508, ora personal computer equipped with an application transmitting traffic toa remote server.

One or more base stations 503 . . . 504 may define a correspondingwireless coverage area. The RF radiation 505 . . . 506 of the basestations 503 . . . 504 may carry communications between the WirelessCellular Network/Internet Network 507 and access device 502 according toany of a variety of protocols. For example, RF radiation 505 . . . 506may carry communications according to WiMAX (Worldwide Interoperabilityfor Microwave Access e.g., IEEE 802.16), LTE (long term evolution),microwave, satellite, MMDS (Multichannel Multipoint DistributionService), Wi-Fi (e.g., IEEE 802.11), Bluetooth, infrared, and otherprotocols now known or later developed. The communication between thewireless device 502 and the server 508 may be enabled by any networkingand transport technology for example TCP/IP (transport controlprotocol/Internet protocol), RTP (real time protocol), RTCP (real timecontrol protocol), HTTP (Hypertext Transfer Protocol) or any othernetworking protocol.

According to some of the various aspects of embodiments, an LTE networkmay include many base stations, providing a user plane (PDCP: packetdata convergence protocol/RLC: radio link control/MAC: media accesscontrol/PHY: physical) and control plane (RRC: radio resource control)protocol terminations towards the wireless device. The base station(s)may be interconnected with other base station(s) by means of an X2interface. The base stations may also be connected by means of an S1interface to an EPC (Evolved Packet Core). For example, the basestations may be interconnected to the MME (Mobility Management Entity)by means of the S1-MME interface and to the Serving Gateway (S-GW) bymeans of the S1-U interface. The S1 interface may support a many-to-manyrelation between MMEs/Serving Gateways and base stations. A base stationmay include many sectors for example: 1, 2, 3, 4, or 6 sectors. A basestation may include many cells, for example, ranging from 1 to 50 cellsor more. A cell may be categorized, for example, as a primary cell orsecondary cell. When carrier aggregation is configured, a wirelessdevice may have one RRC connection with the network. At RRC connectionestablishment/re-establishment/handover, one serving cell may providethe NAS (non-access stratum) mobility information (e.g. TAI-trackingarea identifier), and at RRC connection re-establishment/handover, oneserving cell may provide the security input. This cell may be referredto as the Primary Cell (PCell). In the downlink, the carriercorresponding to the PCell may be the Downlink Primary Component Carrier(DL PCC), while in the uplink, it may be the Uplink Primary ComponentCarrier (UL PCC). Depending on wireless device capabilities, SecondaryCells (SCells) may be configured to form together with the PCell a setof serving cells. In the downlink, the carrier corresponding to an SCellmay be a Downlink Secondary Component Carrier (DL SCC), while in theuplink, it may be an Uplink Secondary Component Carrier (UL SCC). AnSCell may or may not have an uplink carrier.

A cell, comprising a downlink carrier and optionally an uplink carrier,is assigned a physical cell ID and a cell index. A carrier (downlink oruplink) belongs to only one cell, the cell ID or Cell index may alsoidentify the downlink carrier or uplink carrier of the cell (dependingon the context it is used). In the specification, cell ID may be equallyreferred to a carrier ID, and cell index may be referred to carrierindex. In implementation, the physical cell ID or cell index may beassigned to a cell. Cell ID may be determined using the synchronizationsignal transmitted on a downlink carrier. Cell index may be determinedusing RRC messages. For example, when the specification refers to afirst physical cell ID for a first downlink carrier, it may mean thefirst physical cell ID is for a cell comprising the first downlinkcarrier. The same concept may apply to, for example, carrier activation.When the specification indicates that a first carrier is activated, itequally means that the cell comprising the first carrier is activated.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in wireless device, base station, radio environment, network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, traffic load, initial systemset up, packet sizes, traffic characteristics, a combination of theabove, and/or the like. When the one or more criteria are met, theexample embodiments may be applied. Therefore, it may be possible toimplement example embodiments that selectively implement disclosedprotocols.

Example embodiments of the invention may enhance time alignment in amulticarrier OFDM communication system. Other example embodiments maycomprise a non-transitory tangible computer readable media comprisinginstructions executable by one or more processors to cause timealignment in a multicarrier OFDM communication system. Yet other exampleembodiments may comprise an article of manufacture that comprises anon-transitory tangible computer readable machine-accessible mediumhaving instructions encoded thereon for enabling programmable hardwareto cause a device (e.g. wireless communicator, UE, base station, etc.)to enhance time alignment in a multicarrier OFDM communication system.The device may include processors, memory, interfaces, and/or the like.Other example embodiments may comprise communication networks comprisingdevices such as base stations, wireless devices (or user equipment: UE),servers, switches, antennas, and/or the like.

A base station may transmit configuration messages to a wireless devicecausing configuration of a first (primary) carrier and one or moresecond (secondary) carriers in the wireless device. Serving carriershaving uplink to which the same time alignment applies may be grouped ina carrier group. Serving carriers in one carrier group may use the sametiming reference. For a given carrier group, a wireless device may useone active downlink carrier as the timing reference at a given time. Fora given carrier group, a wireless device may employ the same timingreference for uplink subframes and frames transmission timing of theuplink carriers belonging to the same carrier group. According to someof the various aspects of embodiments, serving carriers having uplink towhich the same time alignment applies may correspond to the servingcarriers hosted by the same receiver. A carrier group comprises at leastone serving carrier with configured uplink. A wireless device supportingmultiple carrier groups may support two or more carrier groups. Onecarrier group contains the first carrier and may be called a firstcarrier group. In a multiple carrier group configuration, at least onecarrier group, called a second carrier group, may contain one or moresecond carriers and may not contain the first carrier. Carriers withinthe same carrier group may use the same time alignment value and thesame timing reference.

To obtain initial uplink time alignment for a second carrier group, basestation may initiate random access procedure. In a second carrier group,wireless device may use one of any activated second carriers from thesecond carrier group as a timing reference carrier. There may be onetiming reference and one time alignment timer (time alignment timer) percarrier group. Time alignment timer for carrier groups may be configuredwith different values. When the time alignment timer associated with thefirst carrier group expires, all time alignment timers may be consideredas expired and the wireless device may flush all HARQ buffers of allserving carriers, may clear any configured downlink assignment/uplinkgrants, and RRC may release PUCCH/SRS for all configured servingcarriers. When the first carrier group time alignment timer is notrunning, a second carrier group time alignment timer may not be running.When the time alignment timer associated with second carrier groupexpires: a) SRS transmissions may be stopped on the corresponding secondcarriers, b) the type-0 SRS configuration may be released, the type-1SRS configuration may be maintained, c) CSI reporting configuration forthe corresponding second carriers may be maintained, and/or d) MAC mayflush the uplink HARQ buffers of the corresponding second carriers.

Upon deactivation of the last active second carrier in a second carriergroup, the wireless device may not stop time alignment timer of thesecond carrier group. Upon removal of the last second carrier in asecond carrier group, time alignment timer of the carrier group may notbe running. Random access procedures in parallel may not be supportedfor a wireless device. If a new random access procedure is requested(either by wireless device or network) while another random accessprocedure is already ongoing, it may be up to the wireless deviceimplementation whether to continue with the ongoing procedure or startwith the new procedure. The base station may initiate the random accessprocedure via a PDCCH order for an activated second carrier. This PDCCHorder may be sent on the scheduling carrier of this second carrier. Whencross carrier scheduling is configured for a carrier, the schedulingcarrier may be different than the carrier that is employed for preambletransmission. Non-contention based random access procedure may besupported for second carriers of a second carrier group. Upon new uplinkdata arrival the wireless device may not trigger a random accessprocedure on a second carrier. PDCCH order for preamble transmission maybe sent on a different serving carrier than the second carrier in whichthe preamble is sent. Carrier grouping may be performed withoutrequiring any additional wireless device assisted information.

A wireless device may transmit a scheduling request and/or a bufferstatus report due to uplink data arrival in the wireless device. Awireless device may transmit a scheduling request when wireless devicehas data for uplink transmission and wireless device does not receiveuplink grants for transmission of buffer status report. Wireless devicemay transmit a medium access control buffer status report in the uplinkto inform the base station about the size of the uplink transmissionbuffer. A wireless device buffer status report may be transmitted in anuplink resource identified in a received uplink grant. In response toreceiving buffer status report, the base station may, selectively anddepending on a plurality of criteria, transmit a PDCCH order to thewireless device and may cause the wireless device to start random accessprocedure on a second carrier (in case of carrier aggregation). A PDCCHorder may be triggered by the buffer status report reception due to theuplink data arrival in the wireless device. Preamble transmission may betriggered in the case of uplink data arrival, meaning that preambletransmission may be triggered by the buffer status report reception inthe base station. Upon new uplink data arrival the wireless device maynot trigger a random access procedure on a second carrier. The basestation may trigger the random access procedure based on the bufferstatus report reception due to uplink data arrival in the wirelessdevice. Base station may consider many parameters in triggering randomaccess on a second carrier, for example, current base station load,wireless device buffer size(s) in buffer status report report(s),wireless device category, wireless device capability, QoS requirements,and/or the like.

Initial timing alignment may be achieved through random accessprocedure. This involves the wireless device transmitting a randomaccess preamble and the base station responding an initial timealignment command with a time alignment value within the random accessresponse window. The start of the random access preamble may be alignedwith the start of the corresponding uplink subframe at the wirelessdevice assuming time alignment value of zero. The base station mayestimate the uplink timing from the random access preamble transmittedby the wireless device. Then the time alignment command may be derivedby the base station based on the estimation of the difference betweenthe desired uplink timing and the actual uplink timing. The wirelessdevice may determine the initial uplink transmission timing relative tothe corresponding downlink of the second carrier group on which thepreamble is transmitted. PDCCH order may be used to trigger randomaccess process for an activated second carrier. For a newly configuredsecond carrier or a configured but deactivated second carrier, basestation may need to firstly activate the corresponding second carrierand then trigger random access process on it.

According to some of the various aspects of embodiments, a base stationmay communicate with a mix of wireless devices. Wireless devices maysupport multiple technologies, or multiple releases of the sametechnology depending on wireless device category and/or capability. Abase station may comprise multiple sectors. When specification refers toa base station communicating with a plurality of wireless devices,specification may refer to a subset of the total wireless devices in thecoverage area. Specification may refer to for example a plurality ofwireless devices of a given LTE release with a given capability and in agiven sector of the base station. The plurality of wireless devices inthe specification may refer to a selected plurality of wireless devices,or a subset of total wireless devices in the coverage area, whichperform according to the disclosed methods. There may be many wirelessdevices in the coverage area that may not comply with the disclosedmethods, for example because those wireless devices perform based onolder releases of LTE technology. The number of time alignment commandstransmitted by the base station to a wireless device in a given periodmay depend, at least in part, on many parameters including at least oneof: a) speed that the wireless device moves in the coverage area, b)direction that the wireless device moves in the coverage area, c)coverage radius, d) number of active wireless devices in the coveragearea, and/or the like.

According to some of the various aspects of embodiments, the mapping ofa serving carrier to a carrier group may be configured by the servingbase station with RRC signaling. When needed, the mapping between asecond carrier and a carrier group may be reconfigured with RRCsignaling. The mapping between a second carrier and a carrier group maynot be reconfigured with RRC while the second carrier is configured. Thefirst carrier may not change carrier group and may always be a member ofthe first carrier group. When a base station performs second carrieraddition configuration, the related carrier group configuration may beconfigured for the second carrier. Base station may modify carrier groupconfiguration of a second carrier by removing (releasing) the secondcarrier and adding a new second carrier (with same physical carrier IDand frequency) with an updated carrier group index. The new secondcarrier with the updated carrier group index may be initially inactivesubsequent to joining the updated carrier group index. Base station mayactivate the updated new second carrier and then start schedulingpackets on the activated second carrier. It may not be possible tochange the carrier group associated with a second carrier but rather thesecond carrier needs to be removed and a new second carrier needs to beadded with another carrier group.

A base station may perform initial configuration based on an initialconfiguration parameters received from a network node (for example amanagement platform), an initial base station configuration, wirelessdevice location, wireless device type, wireless device CSI feedback,wireless device uplink transmissions (for example, data, SRS, and/or thelike), a combination of the above, and/or the like. For example, initialconfiguration may be based on wireless device channel statemeasurements. For example, depending on the signal quality received froma wireless device on various second carriers downlink carrier or bydetermination of wireless device being in repeater coverage area, or acombination of both, a base station may determine the initialconfiguration of first and second carrier groups and membership ofsecond carriers to carrier groups.

In an example implementation, the time alignment value of a servingcarrier may change, for example due to wireless device's mobility from amacro to a repeater or an RRH (remote radio head) coverage area. Thesignal delay for that second carrier may become different from theoriginal value and different from other serving carriers in the samecarrier group. In this scenario, base station may relocate this timealignment-changed serving carrier to another existing carrier group. Oralternatively, the base station may create a new carrier group for thesecond carrier, based on the updated time alignment value. Timealignment value may be derived for example through base stationmeasurement of signal reception timing, random access procedure, and/orother standard or proprietary algorithms. A base station may realizethat the time alignment value of a serving carrier is no longerconsistent with its current carrier group. There may be many otherscenarios which require base station to reconfigure carrier groups.During reconfiguration, the base station may need to move the referencesecond carrier belonging to a second carrier group to another carriergroup. In this scenario, the second carrier group would require a newreference second carrier. In an example embodiment, the wireless devicemay select an active second carrier in the second carrier group as thereference timing second carrier.

Base station may consider wireless device's capability in configuringmultiple carrier groups for a wireless device. Wireless device may beconfigured with a configuration that is compatible with wireless devicecapability. Multiple carrier group capability may be an optional featurein LTE release 11 and per band combination of multiple carrier groupcapability may be introduced. Wireless device may transmit its multiplecarrier group capability to base station via an RRC message and basestation may consider wireless device capability in configuring carriergroup configuration of the wireless device.

The time alignment maintenance for the first carrier and first carriergroup may follow Rel-10 principles. If a second carrier applying thetime alignment of the first carrier is added to the first carrier group,the Rel-10 procedures may be reused. In one example embodiment, there isno need to assign a carrier group index for the first carrier group.Second carriers grouped with the first carrier may be grouped implicitlyand a carrier group index for the first carrier group may not be neededor a carrier group index may be assigned implicitly by default (forexample, carrier group index 0). Carrier group index may be regarded aszero if the carrier group index field is absent upon second carrieraddition. If a second carrier is not configured with a carrier groupindex, it may apply that the second carrier belongs to first carriergroup.

According to some of the various aspects of embodiments, a wirelessdevice may select one second carrier downlink in a secondary carriergroup as the downlink timing reference carrier for the secondary carriergroup. This may reduce signaling overhead or complexity ofimplementation and/or increase efficiency. For a wireless device, asecond carrier group may have one timing reference carrier. In anexample embodiment, the active second carrier with the highest signalquality may be selected as the timing reference second carrier by thewireless device. In another example embodiment, downlink timingreference carrier for a second carrier group may be the second downlinkcarrier associated with the second uplink carrier where random accessprocess was performed. For preamble transmission, the correspondingdownlink of the carrier which the preamble is sent may be used asdownlink timing reference. In an example embodiment, wireless device mayautonomously select a downlink carrier of an active carrier in thesecond carrier group as the reference second carrier. When timealignment command is received in random access response or timingalignment command for a carrier group, the wireless device may apply thetime alignment value to current uplink timing of the correspondingcarrier group.

In an example embodiment, the second carrier served as the timingreference carrier in second carrier group may be deactivated in somecases. In a wireless device, when a second carrier is inactive, thewireless device may switch off some parts of the receiver and/ortransmitter corresponding to the second carrier. This act may reducebattery power consumption in the wireless device. In another exampleembodiment, the reference second carrier in a second carrier group maybe released by the serving base station. The timing reference carriermay be changed to another active second carrier in the second carriergroup for maintaining uplink timing alignment for second carriers in thesame second carrier group. Change of timing reference carrier in asecond carrier group may be supported. The reference carrier may also bechanged for other reasons such as coverage quality, random accessprocess failure, reference second carrier release, subscriber mobility,a combination of the above, and/or the like. In an example embodiment,when the reference timing second carrier is released or is deactivated,the wireless device may autonomously change the timing reference carrierto another active second carrier in the second carrier group. Forexample, initially downlink second carrier in which random access istransmitted may be used as a timing reference and then the wirelessdevice may use another second carrier in the carrier group as the timingreference, when the reference second carrier needs to be changed.

A preamble may be sent by a wireless device in response to the PDCCHorder on a second carrier belonging to a second carrier group. Preambletransmission for second carriers may be controlled by the network usingPDCCH order. Random access response message in response to the preambletransmission on second carrier may be addressed to RA-CRNTI in the firstcarrier common search space. Once the random access preamble istransmitted, the wireless device (that transmitted the preamble) maymonitor the PDCCH of the first carrier for random access response(s).Wireless device may monitor the PDCCH in the random access responsewindow. The wireless device may stop monitoring for random accessresponse(s) after successful reception of a random access responsecontaining a random access preamble identifier that matches thetransmitted random access preamble.

If the random access response contains a random access preambleidentifier corresponding to the transmitted random access preamble, thewireless device may consider this random access response receptionsuccessful and apply the random access response for the serving carrierwhere the random access preamble was transmitted. The wireless devicemay process the received timing advance command. The wireless device mayprocess the received uplink grant value and indicate it to the lowerlayers. In an example implementation, the second carrier index in theuplink grant may not be transmitted in the uplink grant in random accessresponse and the uplink grant contained in the random access responsemay be applicable to the carrier where the preamble was sent. Accordingto some of the various aspects of embodiments, preamble identifier maybe included in a random access response to address possible preamblemisdetection by the base station. Wireless device may compare thepreamble identifier in random access response with the transmittedpreamble identifier to verify the validity of the random access responseand to verify possible preamble misdetection by base station. The basestation may transmit at least one RRC message to a wireless devicecausing configuration of random access resources in a wireless device.In the first carrier group, random access resources may be configured onthe first carrier, and no second carrier in the first carrier group maybe configured with random access resources. One or more second carriersin a second carrier group may be configured with random accessresources. This may allow the base station to trigger random accessprocess on any one of the second carriers (in the second carrier group)that is configured with random access resources. For the first carriergroup, random access process may be performed only on the first carrier.This feature may provide flexibility to the base station in selecting asecond carrier for random access process in a second carrier group. Itmay be noted that carrier configuration may be wireless device specific,and two wireless devices may be configured with different first carrierand different carrier group configurations.

If a wireless device receives an RRC message that causes the wirelessdevice to be configured to transmit sounding reference signal on asecond carrier, the wireless device may transmit sounding referencesignal if the second carrier is in-sync. The second carrier is in-sync,if time alignment timer for the corresponding second carrier group isrunning. In an example embodiment, if a second carrier is configured andis associated with a second carrier group that is out-of-sync (timealignment timer is not running), the base station may initiate randomaccess process on a second carrier in the second carrier group. Inresponse to successful completion of random access process in the secondcarrier group, the wireless device may start sounding reference signaltransmission on uplink carriers of second carriers (in the secondcarrier group) with configured sounding reference signal transmission.Wireless device may not transmit sounding reference signal in the uplinkof a second carrier belonging to an out-of-sync second carrier group.When sounding reference signal is configured for a second carrierbelonging to an out-of-sync second carrier group, a wireless device maynot send sounding reference signal until wireless device receives arandom access response including a time alignment value, and an uplinkgrant, because otherwise sounding reference signal may be sent withincorrect transmission power and/or timing. Uplink grant may includepower control information. The wireless device may receive timealignment value, uplink resources and a power control command to adjustthe uplink transmission timing and power before the wireless devicestarts to send sounding reference signal (if configured for the secondcarrier).

If no random access response is received within the random accessresponse window, or if none of all received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered not successful and the wireless device may increment apreamble transmission counter by one. If the counter reaches apredefined value and if the random access preamble is transmitted on thefirst carrier, wireless device may indicate a random access problem toRRC layer. The first carrier group may be considered out of sync, anduplink transmissions (except transmission of an uplink preamble) maystop. RRC layer may indicate a radio link failure. If the counterreaches a predefined value and if the random access preamble istransmitted on a second carrier, wireless device may consider the randomaccess procedure unsuccessfully completed. The wireless device may notindicate a random access problem to RRC layer in this case, and no radiolink failure may be indicated. The wireless device may continue uplinktransmissions on that carrier group. The time alignment state of thecarrier group may remain in-sync if the time alignment timer is running.

LTE Rel-8, 9 & 10 timing advance (alignment) command MAC control element(CE) has a fixed size of one octet and contains 2 reserved bits (Rbits). LTE Rel-8, 9 & 10 supports only one carrier group and there is noneed to indicate to which carrier group the time alignment command mayapply. The time alignment command is applied to uplink carriersincluding first carrier and second carrier(s) of a wireless device.There is a need for enhancing the time alignment procedure in LTE Rel-8,9 & 10 to efficiently support multiple carrier groups. In release 11 orabove, when multiple carrier groups are configured, a MAC CE identifyingthe carrier group to which the time alignment value applies may be used.The R bits may be employed to signal the carrier group to which the timealignment value applies. The R bits of the timing advance command MACcontrol elements may be employed to signal the time alignment group. Inthis embodiment, one time alignment is included in a MAC CE. If multipletime alignment, each for a different carrier group, need to betransmitted, then multiple CEs may be transmitted.

According to some of the various aspects of embodiments, when the R bitsare set to 0, MAC CE indicates the carrier group of the first carrier(first carrier group) and other values are addressed to other carriergroups (second carrier groups). This would allow for a maximum of fourtime alignment groups. Zero may be used for the R bits correspond tofirst carrier group, and other values may be used for second carriergroups. This solution may reduce the changes to the release 8, 9, 10 MAClayer, and enhance the MAC CE time alignment command to multiple carriergroups. RRC layer may configure carrier groups for a second carrier(implicitly or explicitly) and may assign a carrier group index to acarrier group. The index that is introduced for a carrier group in RRCmay be employed for the setting of the R bits. Carrier group indexconfigured by RRC may be used to indicate carrier group where the timealignment command applies. This may imply that the RRC signaling mayconfigure up to 4 carrier group indices.

One carrier group in one time alignment command may be supported. R.11or above wireless devices may check R bits in MAC CE, but R.10 or belowwireless devices may not need to check the R bits. According to some ofthe various aspects of embodiments, an R.11 or above wireless devicewith one configured carrier group (first carrier group) may not need tocheck the R bits. A 6-bit time alignment value may be associated with acarrier group using 2-bit carrier group index. This enhancement maysupport transmitting time alignment value for a specific carrier groupwithout adding the size of MAC CE command compared to release 8, 9, 10.Two bits of carrier group index bits are introduced before the 6 bits oftime alignment value. This may require a new definition for MAC CEcommand that would be applicable to release 11 or above wirelessdevices. A method to introduce this new MAC CE command is to introduce anew MAC LCID for this new format. This is a viable implementationoption. This may increase the number of used MAC LCIDs. An embodiment isintroduced here that would allow to use the same MAC LCID as in Rel-8, 9& 10 for Rel-11 multiple carrier group configuration. The same LCID asin Rel-8, 9 & 10 may be used in this embodiment applicable to multiplecarrier group configuration in release 11 or beyond. Base stationtransmits time alignment MAC CEs to wireless devices in unicastmessages. Base station has the information about the current LTE releasesupported by the wireless device. This information may be available tothe base station via network signaling or via air interface signaling(wireless device capability message received from the wireless device).Base station may use the same LCID for the legacy time alignment MAC CEand the newly introduced time alignment MAC CE. If the MAC CE istransmitted to the release 8, 9, 10 LTE wireless devices, then the Rbits may not include a carrier group index. If the MAC CE is transmittedto the release 11 or above wireless devices, then the R bits may includethe carrier group index if multiple carrier groups are configured. Ifmultiple carrier groups are not configured, then time alignment value isapplied all the configured and active carriers.

This enhancement may not require introducing a new LCID, although a newMAC CE format is introduced for transmitting time alignment commands.Both legacy time alignment MAC CEs and new time alignment MAC CEs mayuse the same LCID and that reduces the number of LCIDs used in the MAClayer (compared with the scenario where a new LCID is introduced) andmay further simplify wireless device implementation. Base station mayconsider wireless device LTE release or may consider the number ofconfigured carrier groups (1 for first carrier group only configuration,more than 1 for first carrier group and second carrier groupconfiguration) to decide if legacy MAC CE format should be used or newMAC CE format should be used. If a wireless device is a release 8, 9,10, then legacy MAC CE is used. For release 11 or above wireless deviceswith one carrier group configuration (only first carrier group), basestation may use legacy MAC CE, or use new MAC CEs with RR bits set tofirst carrier group index (for example 0 for first carrier group). Forrelease 11 or above wireless devices (or for release 11 or abovewireless devices with multiple carrier group configuration), basestation may use the new MAC CE format, wherein RR bits set to thecarrier group index, which was configured in wireless device employingRRC configuration messages.

In an example, wireless devices (for example: wireless device1, wirelessdevice2) communicating with a base station may support differentreleases of LTE technology. For example, wireless device2 may supportreleases 8, 9, 10, and 11 of LTE, and wireless device1 may supportreleases 8, 9 and 10 (or for example may support release 8, or maysupport 8 & 9). In another example, wireless devices (for example:wireless device1, wireless device2) communicating with a base stationmay support different capabilities of LTE technology. For example,wireless device2 may support multiple carrier groups, and wirelessdevice1 may not support multiple carrier groups. Base station may sendMAC time alignment CEs to the wireless devices (wireless device1,wireless device2) in unicast messages. MAC time alignment CEs may havethe same LCID for wireless device1 and wireless device2. The wirelessdevices (wireless device1, wireless device2) may interpret MAC timealignment CE messages for adjusting uplink timing differently dependenton the LTE release they support and are operating. The same exactmessage may be processed differently by wireless device1 and wirelessdevice2. For example, in a scenario, where MAC LCID indicate MAC timealignment CE, and RR field is 00, wireless device1 may not consider thevalue of the two bits before time alignment value (RR). Wireless device1may change the uplink transmission timing for all configured and activeuplink carriers according to the time alignment value in the MACcommand. Wireless device2 may however, decode the value of two bitsbefore time alignment value (RR=carrier group index), and when the twobits are for example 00, wireless device1 may only update thetransmission timing for active carriers belonging to first carrier groupaccording to the time alignment value. The first two bits may indicatethe carrier group index to which the time alignment may apply.Therefore, the same MAC CE message content may be processed differentlyby different wireless devices operating in different LTE releases. Inanother example embodiment, multiple carrier groups feature may be anoptional feature in release 11. Wireless device1 may be a release 11wireless device without multiple carrier group capability. Wirelessdevice2 may be a release 11 (or above) wireless device with multiplecarrier group capability. A wireless device with multiple carrier groupcapability may also operate in a single time alignment mode depending onbase station release and/or network configuration (one carrier groupconfiguration). For example, when a multiple carrier group release 11wireless device communicate to a release 10 base station, it mayinterpret all base station commands as release 10 commands.

According to some of the various aspects of embodiments, a base stationmay transmit a plurality of unicast timing advance commands to aplurality of wireless devices for adjusting uplink transmission timingby the plurality of wireless devices. Each of the plurality of wirelessdevices may operate in a mode. The mode may comprise: a) a first modeemployable by all of the plurality of wireless devices, or a second modeemployable only by a subset of the plurality of wireless devices. Eachof the plurality of wireless devices being addressed by at least one ofthe plurality of unicast timing advance commands may interpretdifferently the at least one of the plurality of unicast timing advancecommands depending on the mode in which each of the plurality ofwireless devices is operating. The plurality of unicast timing advancecommands may have the same format for the plurality of wireless devicesoperating in the first mode and the plurality of wireless devicesoperating in the second mode. The format may comprise: a) a subheaderbeing the same for the plurality of unicast timing advance commands, andb) a control element comprising a timing advance value. The first modemay be configured to be compatible with release 10 of LTE-Advancetechnology. The second mode may be configured to be compatible withrelease 11 of LTE-Advance technology.

During the connection establishment process, a base station may transmita first control message to a wireless device (wireless device) on afirst downlink carrier of a first carrier to establish a first signalingbearer with the wireless device on the first carrier. The wirelessdevice may transmit radio capability parameters to the base station onthe first signaling bearer on a first uplink carrier of the firstcarrier.

According to some of the various aspects of embodiments, radiocapability parameters may include a parameter indicating support formultiple carrier groups. Support for multiple carrier groups may beconsidered an optional feature in release 11, and a base station may notknow if a wireless device supports multiple carrier groups capabilitiesuntil it receives a wireless device capability message from the wirelessdevice indicating that the wireless device supports multiple carriergroups feature. Before base station configures first carrier group andsecond carrier group(s), base station may receive and process wirelessdevice capability regarding wireless device multiple carrier groupscapabilities. Supporting multiple carrier group capability may requirethat wireless device includes new hardware and/or software features thatprovide such a capability. Multiple time alignment capability may be anoptional capability for Rel-11 wireless device and its support maydepend on wireless device's hardware, DSP, software designs, and/or thelike. A wireless device may send at least one time alignment capabilityparameter to the base station. Base station may configure wirelessdevice's second carrier group(s) and first carrier group within thewireless device capability. For example, a wireless device may indicatehow many second carrier groups it may support. Base station mayconfigure wireless device second carrier group(s) based, at least inpart, on the number of supported second carrier groups in a wirelessdevice. In another example, wireless device may explicitly or implicitlyindicate if it supports inter-band or intra-band multiple carriergroups, or both. In an example embodiment, support for multiple carriergroups may be mandatory in release 11. A base station may find out aboutmultiple carrier group capability employing information exchangedbetween the wireless device and the base station.

According to some of the various aspects of embodiments, multiplecarrier group capability may be explicitly or implicitly communicated tobase station. In an example embodiment, inter-band and/or intra-bandcarrier aggregation may be configured with multiple carrier groups.Wireless device may send multiple carrier group capability based on eachsupported band combinations. Wireless devices that could be configuredwith inter-band carrier aggregation may need multiple carrier groups(multiple time alignment) configuration. Carriers in a band mayexperience a different delay compared with a different band and a bandmay need its own carrier group configuration. A carrier groupconfiguration for carriers for a band may be required. In a multipleband wireless device, multiple carrier groups may be configured, forexample one carrier group per band. Wireless device may comprise aplurality of RF chains to support inter-band carrier aggregation. Awireless device may support multiple carrier groups if the wirelessdevice support inter-band carrier aggregation. In an example embodiment,when a wireless device transmits wireless device band combinationinformation for inter-band carrier aggregation, it may imply that thatwireless device supports multiple carrier groups for those bands, andtransmission of a separate information element for multiple carriergroup capability may not be required.

A wireless device transceiver architecture may support non-contiguousand/or contiguous carrier aggregation in intra-band. Wireless device maysupport multiple carrier groups in partial or all supportable intra-bandcarrier aggregation. Support for multiple carrier groups may depend onwireless device structure, and some wireless devices may not supportintra-band multiple carrier group configurations depending on wirelessdevices transceiver structure. In an example embodiment, a wirelessdevice may communicate its multiple carrier group capability to the basestation for intra-band communication. A wireless device may transmit themultiple carrier group capability information for contiguous intra-bandcarrier aggregation and/or non-contiguous intra-band carrieraggregation. In another example embodiment, a wireless device may alsocommunicate wireless device inter-band carrier group capability to thebase station.

According to some of the various aspects of embodiments, a wirelessdevice may indicate its multiple carrier group capability in differentinformation elements for inter-band and intra-band multiple carriergroup capability. Each information element may have its own format. Inan example embodiment, multiple carrier group capability for intra-bandand/or inter-band may be communicated employing at least one parameterand may comprise an index, for example, a band combination index, aconfiguration index, a band-type index, a combination of the above,and/or the like. The base station may employ an internally storedlook-up table to interpret the index. Wireless device may transmit atleast one parameter including the index to the base station. The basestation may use a set of pre-stored configuration options (for examplein a look-up table, information list, a stored file, and/or the likeformat). The base station may receive the index and determine some ofthe multiple carrier groups capabilities according to the index. Forexample, an index three may indicate a multiple carrier group capabilitysupporting band A and band B. In another example, an index four mayindicate a multiple carrier group capability of a pre-define intra-bandconfiguration. These configurations are for example only and otherexamples employing configuration index may be possible. The indexing mayreduce the number bits employed for transmitting multiple carrier groupcapability to the base station.

In an example embodiment, a wireless device may indicate its multiplecarrier group capability in an information elements for inter-band andintra-band multiple carrier group capability. All the possibleinter-band and intra-band combinations may be transmitted in the sameinformation element field and a base station may detect wireless deviceinter-band and intra-band capability employing the received informationelement, for example, in a wireless device capability message. In animplementation option, an index may be employed to indicate bothinter-band and intra-band configuration options.

According to some of the various aspects of embodiments, a base stationmay receive (explicitly or implicitly) information about whether awireless device supports multiple carrier group capability using networksignaling on an interface to the core network (for example the interfaceto mobility management entity). This information may be received from amobility management entity during the RRC connection signaling. Some ofthe multiple carrier groups options may be considered supported bydefault or may be considered supported based on some other capabilityparameters. For example, any wireless device supporting inter-bandcarriers and supporting multiple carrier groups feature may be assumedthat is supporting inter-band multiple time alignments. Or for example,intra-band time alignment may be considered a default feature of thewireless device supporting multiple carrier groups feature. In anotherexample, support for intra-band time alignment may need to be explicitlyreported to base station by the wireless device.

In an example embodiment, both inter-band and intra-band carrieraggregation may support multiple carrier groups configurations. Forexample, carriers in the same carrier group may be in the same ordifferent bands. In another example, carriers in the same band maybelong to same or different carrier groups. In an example embodiment,carrier group configuration may not be band-specific and may work withthe current wireless device working band combination. In anotherexample, a wireless device may report its multiple carrier groupcapability based on supported band combinations. Support for multiplecarrier group configurations may imply that one or more of the followingfeatures are supported by the wireless device: i) Parallel transmissionof a preamble on a second carrier uplink carrier (second carrier PRACH)and PUSCH on at least one other carrier; ii) Parallel transmission of apreamble on second carrier uplink carrier (second carrier PRACH) andPUCCH on at least one other carrier, for example the first carrier; iii)Parallel transmission of preamble on second carrier uplink carrier,PUCCH (for example on first carrier), and PUSCH on at least one othercarrier. This feature may be supported if parallel transmission of PUCCHand PUSCH is supported by the wireless device; iv) Processing MAC timealignment CE commands including carrier group index. The wireless devicemay apply the time alignment value to the proper carrier group accordingto carrier group index in the MAC time alignment CE; v) Running randomaccess process on a second carrier belong to a second carrier group.This feature may require transmission of random access preamble on anuplink carrier belonging to a second carrier of a second carrier group;vi) Maintaining more than one time alignment timer in the wirelessdevice; vii) Grouping carriers into multiple carrier groups, wherein acarrier group timing is managed based, at least in part, on a differenttiming reference second carrier and time alignments associated with acarrier group. A wireless device may need to synchronize and tracksynchronization signals of multiple downlink carriers, one referencecarrier synchronization signal for a carrier group. A carrier group mayhave its own timing reference second carrier, which is different thanthe timing reference carrier of another carrier group.

In an example embodiment, a wireless device supporting multiple carriergroups feature may support one or more of the above features. Forexample, the supported feature may be based, at least in part, on theparameters of the wireless device capability message and otherpredetermined parameters (explicitly or implicitly determined bysignaling messages or technology specifications) and/or other signalingmessages. In an example embodiment, a wireless device supportingmultiple carrier groups feature may support all the features itemizedabove. A wireless device that does not support multiple carrier groupsfeature may support none of the above features. In another exampleembodiment, a wireless device supporting multiple carrier groups featuremay support all the above features. A wireless device that does notsupport multiple carrier groups feature may not support all-of-the-abovefeatures.

According to some of the various aspects of embodiments, the basestation may transmit a synchronization signal on a first downlinkcarrier via the communication interface. The synchronization signal mayindicate a physical cell ID for the first carrier. The synchronizationsignal may provide timing information for the first downlink carrier. Inan example embodiment, the synchronization signal may be a signal with apre-defined structure that is transmitted at a predefined time andsubcarriers. FIG. 7 depicts message flows between a base station 602 anda wireless device 601 as per an aspect of an embodiment of the presentinvention. The base station 602 may receive a random access preamble 703on a second plurality of subcarriers from the wireless device 601 on afirst uplink carrier in the plurality of uplink carriers. The firstuplink carrier corresponds to the first downlink carrier. The timing ofthe random access preamble is determined based, at least in part, on thesynchronization signal timing and many other parameters includingparameters received from the base station by the wireless device. Thebase station 602 may transmit a long time alignment command 704 in arandom access response to the wireless device 601 on a third pluralityof subcarriers on the first downlink carrier. The long time alignmentcommand may indicate an amount of required time adjustment for signaltransmission on the first uplink carrier.

The base station may transmit at least one configuration message 705 tothe wireless device. The at least one configuration message isconfigured to configure at least one additional carrier (also calledsecondary carrier or second carrier) in the wireless device. Anadditional carrier in the at least one additional carrier may comprisean additional downlink carrier and zero or one additional uplinkcarrier. The base station may also configure carrier groups comprising afirst carrier group and a second carrier group. The first carrier groupincludes the first carrier and zero or more additional carrier. Thesecond carrier group includes at least one of the at least oneadditional carrier. The base station may also transmit an activationcommand 705 to the wireless device. The activation command may beconfigured to activate in the wireless device at least one of at leastone additional carrier.

The base station 602 may transmit a control command to the wirelessdevice 601 for transmission of a random access preamble on one of theadditional uplink carriers of the second carrier group. The base stationmay transmit a random access response containing a long time alignmentcommand in response to reception of said random access preamble. Thebase station may transmit signals to the wireless device on the firstdownlink carrier and at least one additional downlink carrier. Thesignals may carry control packets or data packets, or may be physicallayer signals. Frame and subframe transmission timing of the firstdownlink carrier and the at least one additional downlink carrier may besubstantially synchronized. Base station 602 may receive signals 706from the wireless device 601 on the first uplink carrier and the atleast one additional uplink carrier. The received signals 706 may carrycontrol or data packets, or may be physical layer signals. The basestation 602 may transmit at least one short time alignment command 707to the wireless device 601. The short time alignment command comprisesat least one short time alignment entity. Each short time alignmententity may comprise: a) an amount of time adjustment, and b) an indexidentifying a carrier group. Long time alignment commands are containedin random access responses. Short time alignment commands are containedin MAC time alignment command control elements.

FIG. 6 illustrates the subframe timing as per an aspect of an embodimentof the present invention. The subframe signals of carrier zero 603,carrier one 604 and carrier two 605 are transmitted by the wirelessdevice 601. Carriers are divided into two groups. The first groupincludes carrier 0 and carrier 1, and the second group includes carrier2. The signals of a carrier may experience a different transmissiondelay compared to another carrier. In an example, the signals receivedfrom carrier zero 603 and carrier one 604 require TA1 606, and thesignals received from carrier two 605 requires TA2 607 in order to bealigned with the reference time 608 at the base station 602. Basestation 602 transmits time alignment commands to the wireless device.The time alignment commands are configured to cause adjustment ofcarrier(s) transmission time. The time alignment value for differentcarrier groups may be different. Upon reception of the commands by thewireless device 601, the wireless device 601 may adjust uplink carriersignal timings of the corresponding carrier group accordingly. Then thereceived signals at the base station 602 may become substantiallysynchronized with the signals received from other wireless devices (notshown in the FIG. 6). In this example, signal reception time of carrierzero 603, carrier one 604 and carrier two 605 are to be substantiallysynchronized at the base station 602.

According to some of the various aspects of embodiments, the primarysynchronization signal may be generated employing a frequency-domainZadoff-Chu sequence. The primary synchronization signal may be mapped tothe last OFDM symbol in slots 0 and 10 for FDD frame structure. Theprimary synchronization signal may be mapped to the third OFDM symbol insubframes 1 and 6 for TDD frame structure. The secondary synchronizationsignal may be generated employing an interleaved concatenation of twolength-31 binary sequences. The concatenated sequence may be scrambledwith a scrambling sequence given by the primary synchronization signal.The secondary synchronization signal may differ between subframe 0 andsubframe 5. The timing information provided by synchronization signalmay comprise subframe timing and frame timing.

The base station may transmit a control command, for example in the formof a PDCCH order, to the wireless device initiating transmission of therandom access preamble by the wireless device. In the first carriergroup, the transmission of the random access preamble on the firstcarrier may be initiated by the MAC sub-layer in the wireless device.The base station may transmit random access parameters to the wirelessdevice. The parameters may be employed for generating a random accesspreamble by the wireless device. The parameters may also be employed fordetermining a transmission time for the random access preamble by thewireless device. The long time alignment command transmitted by the basestation may be included in a random access response message. Theconfiguring task of the at least one additional carrier may compriseconfiguring at least one of a physical layer parameter, a MAC layerparameter and an RLC layer parameter. The activating task of a carrierin the at least one additional carrier in the wireless device maycomprise processing the received signal of the carrier by the wirelessdevice. The activating task may also comprise the wireless devicepotentially transmitting packets/signals employing the carrier. Theremay be at least a guard band between two carriers.

According to some of the various aspects of embodiments, the randomaccess procedure may be initiated by a physical downlink control channel(PDCCH) order or by the MAC sublayer in the wireless device. If awireless device receives a PDCCH message consistent with a PDCCH ordermasked with its radio identifier, it may initiate a random accessprocedure. Preamble transmission on physical random access channel(PRACH) may be supported on the uplink carrier and reception of a PDCCHorder may be supported on the downlink carrier. Before the wirelessdevice initiates transmission of a random access preamble, it may accessone or many of the following information: a) the available set of PRACHresources for the transmission of the random access preamble, b) thegroups of random access preambles and the set of available random accesspreambles in each group, c) the random access response window size, d)the power-ramping factor, e) the maximum number of preambletransmissions, f) the initial preamble power, g) the preamble formatbased offset, h) the contention resolution timer, and/or the like. Theseparameters may be updated from upper layers or may be received from thebase station before a random access procedure is initiated.

The wireless device may select a random access preamble using theavailable information. The preamble may be signaled by the base stationor it may be randomly selected by the wireless device. The wirelessdevice may determine the next available subframe containing PRACHpermitted by the restrictions given by the base station and physicallayer timing requirements for TDD or FDD. Subframe timing and the timingof transmitting the random access preamble may be determined based onthe synchronization signals received from the base station and theinformation received from the base station. The wireless device mayproceed to the transmission of the random access preamble when it hasdetermined the timing. The random access preamble is transmitted on asecond plurality of subcarriers on the first uplink carrier.

Once the random access preamble is transmitted, the wireless device maymonitor the PDCCH of the first downlink carrier for random accessresponse(s) identified by the RA-RNTI during the random access responsewindow. RA-RNTI is the identifier in PDCCH that identifies a randomaccess response. The wireless device may stop monitoring for randomaccess response(s) after successful reception of a random accessresponse containing a random access preamble identifier that matches thetransmitted random access preamble. Base station random access responsemay include a long time alignment command. The wireless device mayprocess the received long time alignment command and adjust its uplinktransmission timing according the time alignment value in the command.For example, in a random access response, long time alignment commandmay be coded using 11 bits, where an amount of the time alignment isbased on the value in command. When an uplink transmission is required,the base station may provide the wireless device a grant for uplinktransmission.

If no random access response is received within the random accessresponse window, or if none of all received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered not successful and the wireless device may, based onthe backoff parameter in the wireless device, select a random backofftime. The wireless device may delay the subsequent random accesstransmission by the backoff time, and may retransmit another randomaccess preamble. The wireless device may transmit packets on the firstuplink carrier and the at least one additional uplink carrier. Uplinkpacket transmission timing for a carrier group may be obtained in thewireless device employing, at least in part, timing of a synchronizationsignals received in a downlink carrier of the carrier group. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust the uplink transmission timing of thecorresponding carrier group. The timing alignment command may indicatethe change of the uplink timing relative to the current uplink timing ofthe carrier group. Adjustment of the uplink timing by a positive or anegative amount indicates advancing or delaying the uplink transmissiontiming by a given amount respectively.

FIG. 8 and FIG. 10 depict example flow charts for a time alignmentprocess in a wireless device as per an aspect of an embodiment of thepresent invention. According to some of the various aspects ofembodiments, the wireless device may receive at least one controlmessage from a base station. The at least one control message mayconfigure a plurality of carriers and a plurality of carrier groups.Each carrier group may comprise at least one downlink carrier and atleast one uplink carrier. The uplink carriers in a carrier group mayemploy the same timing reference. The wireless device may receive anactivation command from the base station. The activation command mayactivate at least one carrier of a carrier group in the plurality ofcarrier groups. The wireless device may receive a control command fromthe base station. The control command may direct the wireless device toinitiate random access procedure on an uplink carrier of a carriergroup. The wireless device may obtain initial uplink timing alignmentfor the carrier group, through the initiated random access procedure.

The wireless device may transmit data on a subset of subframes in theplurality of subframes on a subset of at least one uplink carrier in thecarrier group. The random access procedure may be a non-contention basedrandom access procedure. The at least one control message may be atleast one unicast RRC control message and may comprise at least one of:a) a plurality of carrier group identifiers, and b) a carrier indexassociated to configured carriers. Each carrier may be associated with acarrier group identifier in the plurality of carrier group identifiers.The activation command may be a MAC activation command received from aserving base station. The activation command may activate at least onecarrier of a carrier group in the plurality of carrier groups. The MACactivation command may comprise the carrier index of the carries to beactivated. The control command may be a PDCCH control message from thebase station. The PDCCH control message may direct the wireless deviceto initiate random access procedure on an uplink carrier of the carriergroup. The PDCCH message may comprise a preamble index.

The wireless device may initiate a random access procedure bytransmitting a random access preamble corresponding to the preambleindex. The random access preamble may be transmitted in a plurality ofrandom access resources configured by the base station. The wirelessdevice may obtain initial uplink timing alignment for the carrier group,through the initiated random access procedure. The wireless device maytransmit data on a subset of subframes in the plurality of subframes ona subset of at least one uplink carrier in the carrier group. The randomaccess procedure may be a non-contention based random access procedure.The wireless device may maintain a separate timing alignment timer foreach carrier group in the plurality of carrier groups.

The PDCCH control message may be received on the scheduling downlinkcarrier of the uplink carrier. Multiple random access preambles may betransmitted in a plurality of random access resources in the samesubframe by various wireless devices. The at least one unicast RRCcontrol message may further comprise the configuration of the randomaccess resources. Uplink timing reference for the carrier group may bemaintained, at least in part, using MAC time alignment messages. ThePDCCH message may further include a carrier index. The PDCCH message mayfurther include a power control command. PDCCH message may be scrambledusing an identifier of the wireless device.

Serving carriers having uplink to which the same time alignment appliesmay be grouped in a time alignment group or a carrier group. Eachcarrier group may include at least one downlink carrier with at leastone configured uplink carrier. The mapping of each downlink carrier to acarrier group may be configured by the serving base station employingRRC message(s). Time alignment maintenance for the carrier groupcontaining the primary carrier may follow the release 8, 9 or 10 of LTEstandard for time alignment maintenance. To obtain initial uplink timealignment for a secondary downlink carrier not grouped together with theprimary downlink carrier, base station may initiate a random accessprocedure. The number of time alignment timer to be maintained may beone per carrier group. Time alignment timers may be configured by thebase station. The random access procedure on secondary carriers may beinitiated by the base station. The base station may initiate the randomaccess procedure via a control message (for example a PDCCH order) foran activated secondary carrier. Non-contention based random accessprocedure may be supported. Cross-carrier scheduling may take place inthe random access procedure for transmission of PDCCH order.

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one RRC control message from a base station.The at least one RRC control message may cause configuration of aplurality of carriers comprising a first carrier and at least one secondcarrier. The configuration may associate with a second carrier in the atleast one second carrier: a carrier group index, a second uplinkcarrier, a plurality of random access resource parameters, and/or thelike. The carrier group index may identify a second carrier group. Thesecond carrier group may be one of a plurality of carrier groups. Thesecond carrier group may comprise a second subset of the at least onesecond carrier. The plurality of random access resource parameters mayidentify random access resources.

The wireless device may receive from the base station, a controlcommand. The control command may cause the wireless device to transmit arandom access preamble on the second uplink carrier. The control commandmay comprise a preamble index corresponding to the random accesspreamble. The wireless device may transmit the random access preamble onthe random access resources on the second uplink carrier. Transmissiontiming of the random access preamble may be determined, at least inpart, by employing a synchronization signal transmitted on one of atleast one downlink carrier in the second carrier group. Uplinktransmissions in the second carrier group may employ the synchronizationsignal as timing reference.

The wireless device may receive a long time alignment command on thefirst carrier in response to the random access preamble transmission.The long time alignment command may comprise the preamble index and along time adjustment value. The wireless device may receive at least oneshort time alignment command from the base station. The short timealignment command may comprise a short time adjustment value and anindex. The short time adjustment value range may be substantiallysmaller than the long time adjustment value range. The index mayidentify the second carrier group. The wireless device may apply thetime adjustment value to uplink signals transmitted on all activateduplink carriers in the second carrier group. The wireless device mayapply the time adjustment value such that the base station receivessubstantially aligned uplink signals in frames and subframes of thesecond carrier group.

According to some of the various aspects of embodiments, the long timealignment command may not comprise an index identifying the secondcarrier group. The long time alignment command may comprise a preambleindex. The short time alignment command may not comprise a preambleindex. The short time alignment command may comprise an indexidentifying the second carrier group. The plurality of carrier groupsmay further comprise a first carrier group comprising a first subset ofthe plurality of carriers. The first subset may comprise the firstcarrier with a first downlink carrier and a first uplink carrier. Uplinktransmissions by the wireless device in the first carrier group mayemploy a first synchronization signal transmitted on the first downlinkcarrier as timing reference.

Transmission of the control command may be initiated by a MAC sub-layerin the base station. The wireless device may receive random accessparameters from the base station. The parameters may be configured to beemployed in the generation of the random access preamble by the wirelessdevice. The random access parameters may be configured to be employed inthe determination of the random access preamble transmission time.

The long time alignment command may be received in a random accessresponse message. In an example embodiment, the long time adjustmentvalue may be encoded employing 11 bits. The short time alignment valuemay be encoded employing 6 bits.

FIG. 9 depicts an example flow chart for a time alignment process in abase station as per an aspect of an embodiment of the present invention.The wireless device may receive an activation command from the basestation prior to receiving the control command. The activation commandcausing activation of the second carrier in the wireless device, theactivation causing the wireless device to process downlink receivedsignals on the second carrier.

According to some of the various aspects of embodiments, a base stationmay transmit a first synchronization signal on a first downlink carrierof a first carrier in a plurality of carriers. The base station mayreceive a random access preamble on a first uplink carrier of the firstcarrier. The timing of the random access preamble transmission may bedetermined based, at least in part, on the first synchronization signaltiming. The base station may transmit at least one RRC control message.The at least one RRC control message may cause configuration of at leastone additional carrier in the wireless device. The configuration mayassociate with an additional carrier in the at least one additionalcarrier a carrier group index identifying a second carrier group. Thesecond carrier group may be one of a plurality of carrier groups. Thesecond carrier group may comprise a subset of the at least oneadditional carrier.

The base station may transmit, to the wireless device, signals on thefirst carrier and the at least one additional carrier. Downlink framesand subframes transmission timing for the first carrier and the at leastone additional carrier may be substantially time aligned with eachother. The base station may receive uplink signals from the wirelessdevice on the additional carrier. The base station may transmit, to thewireless device, at least one time alignment command computed based, atleast in part, on timing of the received uplink signals. The timealignment command may comprise a time adjustment value and an indexidentifying the second carrier group. The at least one time alignmentcommand causes substantial alignment of reception timing of uplinksignals in frames and subframes of the second carrier group. Uplinktransmission timing of frames and subframes of the first carrier and theadditional carrier employ different synchronization signals as timingreference and are adjusted in response to different time alignmentcommands.

According to some of the various aspects of embodiments, the firstsynchronization signal comprises a primary synchronization signal and asecondary synchronization signal. The synchronization signal may beconfigured to: indicate a physical carrier ID for the first carrier;provide transmission timing information for the first downlink carrier;be transmitted employing a first plurality of subcarriers, and/or thelike. Transmission time may be divided into a plurality of frames. Eachframe in the plurality of frames may further be divided into a pluralityof subframes. The first plurality of subcarriers may be substantially inthe center of the frequency band of the first downlink carrier on thefirst and sixth subframe of each frame in the plurality of frames.

The base station may generate the primary synchronization signalemploying a frequency-domain Zadoff-Chu sequence. The base station maygenerate the secondary synchronization signal employing an interleavedconcatenation of two 31 bit length binary sequences. The base stationmay scramble the concatenated sequence with a scrambling sequence givenby the primary synchronization signal. The secondary synchronizationsignal may differ between subframe 0 and subframe 5. The timinginformation may comprises subframe timing and frame timing. Theconfiguration of the at least one additional carrier may compriseconfiguring at least one of a physical layer parameter, a MAC layerparameter and an RLC layer parameter.

According to some of the various aspects of embodiments, a base stationmay transmit at least one RRC control message. The at least one RRCcontrol message may cause configuration of a plurality of carrierscomprising a first carrier and at least one additional carrier in thewireless device. The configuration may associate with a carrier in theplurality of carriers a carrier group index identifying a carrier group.The carrier group may be one of a plurality of carrier groups. Theplurality of carrier groups may comprise a first carrier group and asecond carrier group. The first carrier group may comprise a firstsubset of the plurality of carriers. The first subset may comprise thefirst carrier. The second carrier group may comprise a subset of the atleast one additional carrier.

The base station may transmit, to the wireless device, signals on theplurality of carriers. Downlink frames and subframes transmission timingfor the first carrier and the at least one additional carrier may besubstantially time aligned with each other. The base station may receiveuplink signals from the wireless device on the plurality of carriers.The base station may transmit, to the wireless device, at least one timealignment command. The time alignment command may comprise a timeadjustment value and an index identifying one carrier group. Uplinktransmission timing of frames and subframes in the first carrier groupand the second carrier group may employ different synchronizationsignals on different carriers as timing reference and are adjusted inresponse to different time alignment commands.

According to some of the various aspects of embodiments, a base stationmay receive a plurality of radio capability parameters from the wirelessdevice on the first carrier. The plurality of radio capabilityparameters may comprise at least one parameter indicating whether thewireless device supports configuration of a plurality of carrier groups.If the plurality of radio capability parameters may indicate that thewireless device supports configuration of a plurality of carrier groups,the base station may, selectively based on at least one criterion,transmit the at least one RRC control message to cause configuration ofthe plurality of carrier groups in the wireless device. Uplinktransmissions by the wireless device in the first carrier group mayemploys a first synchronization signal transmitted on a first downlinkcarrier of the first carrier as a timing reference. Uplink transmissionsby the wireless device in the second carrier group may employ a secondsynchronization signal transmitted on one of at least one downlinkcarrier in the second carrier group.

According to some of the various aspects of embodiments, a wirelessdevice may receive at least one RRC control message from a base station.The at least one RRC control message may cause configuration of aplurality of carriers comprising a first carrier and at least one secondcarrier. The configuration may associate with a second carrier in the atleast one second carrier: a carrier group index, a second uplinkcarrier, a plurality of random access resource parameters, and/or thelike. The carrier group index may identify a second carrier group. Thesecond carrier group may be one of a plurality of carrier groups. Thesecond carrier group may comprise a second subset of the at least onesecond carrier. The plurality of random access resource parameters mayidentify random access resources.

The wireless device may receive from the base station, a controlcommand. The control command may cause the wireless device to transmit arandom access preamble on the second uplink carrier. The control commandmay comprise a preamble index corresponding to the random accesspreamble. The wireless device may transmit the random access preamble onthe random access resources on the second uplink carrier. Transmissiontiming of the random access preamble may be determined, at least inpart, by employing a synchronization signal transmitted on one of atleast one downlink carrier in the second carrier group. Uplinktransmissions in the second carrier group may employ the synchronizationsignal as timing reference.

The wireless device may receive a long time alignment command on thefirst carrier in response to the random access preamble transmission.The long time alignment command may comprise the preamble index and along time adjustment value. The wireless device may receive at least oneshort time alignment command from the base station. The short timealignment command may comprise a short time adjustment value and anindex. The short time adjustment value range may be substantiallysmaller than the long time adjustment value range. The index mayidentify the second carrier group. The wireless device may apply thetime adjustment value to uplink signals transmitted on all activateduplink carriers in the second carrier group. The wireless device mayapply the time adjustment value such that the base station receivessubstantially aligned uplink signals in frames and subframes of thesecond carrier group.

According to some of the various aspects of embodiments, the long timealignment command may not comprise an index identifying the secondcarrier group. The long time alignment command may comprise a preambleindex. The short time alignment command may not comprise a preambleindex. The short time alignment command may comprise an indexidentifying the second carrier group. The plurality of carrier groupsmay further comprise a first carrier group comprising a first subset ofthe plurality of carriers. The first subset may comprise the firstcarrier with a first downlink carrier and a first uplink carrier. Uplinktransmissions by the wireless device in the first carrier group mayemploy a first synchronization signal transmitted on the first downlinkcarrier as timing reference.

Transmission of the control command may be initiated by a MAC sub-layerin the base station. The wireless device may receive random accessparameters from the base station. The parameters may be configured to beemployed in the generation of the random access preamble by the wirelessdevice. The random access parameters may be configured to be employed inthe determination of the random access preamble transmission time.

The long time alignment command may be received in a random accessresponse message. In an example embodiment, the long time adjustmentvalue may be encoded employing 11 bits. The short time alignment valuemay be encoded employing 6 bits.

The wireless device may receive an activation command from the basestation prior to receiving the control command. The activation commandcausing activation of the second carrier in the wireless device, theactivation causing the wireless device to process downlink receivedsignals on the second carrier.

According to some of the various aspects of embodiments, a base stationmay transmit a first synchronization signal on a first downlink carrierof a first carrier in a plurality of carriers. The base station mayreceive a random access preamble on a first uplink carrier of the firstcarrier. The timing of the random access preamble transmission may bedetermined based, at least in part, on the first synchronization signaltiming. The base station may transmit at least one RRC control message.The at least one RRC control message may cause configuration of at leastone additional carrier in the wireless device. The configuration mayassociate with an additional carrier in the at least one additionalcarrier a carrier group index identifying a second carrier group. Thesecond carrier group may be one of a plurality of carrier groups. Thesecond carrier group may comprise a subset of the at least oneadditional carrier.

The base station may transmit, to the wireless device, signals on thefirst carrier and the at least one additional carrier. Downlink framesand subframes transmission timing for the first carrier and the at leastone additional carrier may be substantially time aligned with eachother. The base station may receive uplink signals from the wirelessdevice on the additional carrier. The base station may transmit, to thewireless device, at least one time alignment command computed based, atleast in part, on timing of the received uplink signals. The timealignment command may comprise a time adjustment value and an indexidentifying the second carrier group. The at least one time alignmentcommand causes substantial alignment of reception timing of uplinksignals in frames and subframes of the second carrier group. Uplinktransmission timing of frames and subframes of the first carrier and theadditional carrier employ different synchronization signals as timingreference and are adjusted in response to different time alignmentcommands.

According to some of the various aspects of embodiments, the firstsynchronization signal comprises a primary synchronization signal and asecondary synchronization signal. The synchronization signal may beconfigured to: indicate a physical carrier ID for the first carrier;provide transmission timing information for the first downlink carrier;be transmitted employing a first plurality of subcarriers, and/or thelike. Transmission time may be divided into a plurality of frames. Eachframe in the plurality of frames may further be divided into a pluralityof subframes. The first plurality of subcarriers may be substantially inthe center of the frequency band of the first downlink carrier on thefirst and sixth subframe of each frame in the plurality of frames.

The base station may generate the primary synchronization signalemploying a frequency-domain Zadoff-Chu sequence. The base station maygenerate the secondary synchronization signal employing an interleavedconcatenation of two 31 bit length binary sequences. The base stationmay scramble the concatenated sequence with a scrambling sequence givenby the primary synchronization signal. The secondary synchronizationsignal may differ between subframe 0 and subframe 5. The timinginformation may comprises subframe timing and frame timing. Theconfiguration of the at least one additional carrier may compriseconfiguring at least one of a physical layer parameter, a MAC layerparameter and an RLC layer parameter.

According to some of the various aspects of embodiments, a base stationmay transmit at least one RRC control message. The at least one RRCcontrol message may cause configuration of a plurality of carrierscomprising a first carrier and at least one additional carrier in thewireless device. The configuration may associate with a carrier in theplurality of carriers a carrier group index identifying a carrier group.The carrier group may be one of a plurality of carrier groups. Theplurality of carrier groups may comprise a first carrier group and asecond carrier group. The first carrier group may comprise a firstsubset of the plurality of carriers. The first subset may comprise thefirst carrier. The second carrier group may comprise a subset of the atleast one additional carrier.

The base station may transmit, to the wireless device, signals on theplurality of carriers. Downlink frames and subframes transmission timingfor the first carrier and the at least one additional carrier may besubstantially time aligned with each other. The base station may receiveuplink signals from the wireless device on the plurality of carriers.The base station may transmit, to the wireless device, at least one timealignment command. The time alignment command may comprise a timeadjustment value and an index identifying one carrier group. Uplinktransmission timing of frames and subframes in the first carrier groupand the second carrier group may employ different synchronizationsignals on different carriers as timing reference and are adjusted inresponse to different time alignment commands.

According to some of the various aspects of embodiments, a base stationmay receive a plurality of radio capability parameters from the wirelessdevice on the first carrier. The plurality of radio capabilityparameters may comprise at least one parameter indicating whether thewireless device supports configuration of a plurality of carrier groups.If the plurality of radio capability parameters may indicate that thewireless device supports configuration of a plurality of carrier groups,the base station may, selectively based on at least one criterion,transmit the at least one RRC control message to cause configuration ofthe plurality of carrier groups in the wireless device. Uplinktransmissions by the wireless device in the first carrier group mayemploys a first synchronization signal transmitted on a first downlinkcarrier of the first carrier as a timing reference. Uplink transmissionsby the wireless device in the second carrier group may employ a secondsynchronization signal transmitted on one of at least one downlinkcarrier in the second carrier group.

In at least one of the various embodiments, uplink physical channel(s)may correspond to a set of resource elements carrying informationoriginating from higher layers. The following example uplink physicalchannel(s) may be defined for uplink: a) Physical Uplink Shared Channel(PUSCH), b) Physical Uplink Control Channel (PUCCH), c) Physical RandomAccess Channel (PRACH), and/or the like. Uplink physical signal(s) maybe used by the physical layer and may not carry information originatingfrom higher layers. For example, reference signal(s) may be consideredas uplink physical signal(s). Transmitted signal(s) in slot(s) may bedescribed by one or several resource grids including, for example,subcarriers and SC-FDMA or OFDMA symbols.

According to some of the various aspects of embodiments, cell search maybe the procedure by which a wireless device may acquire time andfrequency synchronization with a cell and may detect the physical layerCell ID of that cell (transmitter). An example embodiment forsynchronization signal and cell search is presented below. A cell searchmay support a scalable overall transmission bandwidth corresponding to 6resource blocks and upwards. Primary and secondary synchronizationsignals may be transmitted in the downlink and may facilitate cellsearch. For example, 504 unique physical-layer cell identities may bedefined using synchronization signals. The physical-layer cellidentities may be grouped into 168 unique physical-layer cell-identitygroups, group(s) containing three unique identities. The grouping may besuch that physical-layer cell identit(ies) is part of a physical-layercell-identity group. A physical-layer cell identity may be defined by anumber in the range of 0 to 167, representing the physical-layercell-identity group, and a number in the range of 0 to 2, representingthe physical-layer identity within the physical-layer cell-identitygroup. The synchronization signal may include a primary synchronizationsignal and a secondary synchronization signal.

According to some of the various aspects of embodiments, the sequenceused for a primary synchronization signal may be generated from afrequency-domain Zadoff-Chu sequence according to a pre-defined formula.A Zadoff-Chu root sequence index may also be predefined in aspecification. The mapping of the sequence to resource elements maydepend on a frame structure. The wireless device may not assume that theprimary synchronization signal is transmitted on the same antenna portas any of the downlink reference signals. The wireless device may notassume that any transmission instance of the primary synchronizationsignal is transmitted on the same antenna port, or ports, used for anyother transmission instance of the primary synchronization signal. Thesequence may be mapped to the resource elements according to apredefined formula.

For FDD frame structure, a primary synchronization signal may be mappedto the last OFDM symbol in slots 0 and 10. For TDD frame structure, theprimary synchronization signal may be mapped to the third OFDM symbol insubframes 1 and 6. Some of the resource elements allocated to primary orsecondary synchronization signals may be reserved and not used fortransmission of the primary synchronization signal.

According to some of the various aspects of embodiments, the sequenceused for a secondary synchronization signal may be an interleavedconcatenation of two length-31 binary sequences. The concatenatedsequence may be scrambled with a scrambling sequence given by a primarysynchronization signal. The combination of two length-31 sequencesdefining the secondary synchronization signal may differ betweensubframe 0 and subframe 5 according to predefined formula (s). Themapping of the sequence to resource elements may depend on the framestructure. In a subframe for FDD frame structure and in a half-frame forTDD frame structure, the same antenna port as for the primarysynchronization signal may be used for the secondary synchronizationsignal. The sequence may be mapped to resource elements according to apredefined formula.

According to some of the various aspects of embodiments, the physicallayer random access preamble may comprise a cyclic prefix of length Tcpand a sequence part of length Tseq. The parameter values may bepre-defined and depend on the frame structure and a random accessconfiguration. In an example embodiment, Tcp may be 0.1 msec, and Tseqmay be 0.9 msec. Higher layers may control the preamble format. Thetransmission of a random access preamble, if triggered by the MAC layer,may be restricted to certain time and frequency resources. The start ofa random access preamble may be aligned with the start of thecorresponding uplink subframe at a wireless device.

According to an example embodiment, random access preambles may begenerated from Zadoff-Chu sequences with a zero correlation zone,generated from one or several root Zadoff-Chu sequences. In anotherexample embodiment, the preambles may also be generated using otherrandom sequences such as Gold sequences. The network may configure theset of preamble sequences a wireless device may be allowed to use.According to some of the various aspects of embodiments, there may be amultitude of preambles (e.g. 64) available in cell(s). From the physicallayer perspective, the physical layer random access procedure mayinclude the transmission of random access preamble(s) and random accessresponse(s). Remaining message(s) may be scheduled for transmission by ahigher layer on the shared data channel and may not be considered partof the physical layer random access procedure. For example, a randomaccess channel may occupy 6 resource blocks in a subframe or set ofconsecutive subframes reserved for random access preamble transmissions.

According to some of the various embodiments, the following actions maybe followed for a physical random access procedure: 1) layer 1 proceduremay be triggered upon request of a preamble transmission by higherlayers; 2) a preamble index, a target preamble received power, acorresponding RA-RNTI (random access-radio network temporary identifier)and/or a PRACH resource may be indicated by higher layers as part of arequest; 3) a preamble transmission power P_PRACH may be determined; 4)a preamble sequence may be selected from the preamble sequence set usingthe preamble index; 5) a single preamble may be transmitted usingselected preamble sequence(s) with transmission power P_PRACH on theindicated PRACH resource; 6) detection of a PDCCH with the indicated RARmay be attempted during a window controlled by higher layers; and/or thelike. If detected, the corresponding downlink shared channel transportblock may be passed to higher layers. The higher layers may parsetransport block(s) and/or indicate an uplink grant to the physicallayer(s).

According to some of the various aspects of embodiments, a random accessprocedure may be initiated by a physical downlink control channel(PDCCH) order and/or by the MAC sublayer in a wireless device. If awireless device receives a PDCCH transmission consistent with a PDCCHorder masked with its radio identifier, the wireless device may initiatea random access procedure. Preamble transmission(s) on physical randomaccess channel(s) (PRACH) may be supported on a first uplink carrier andreception of a PDCCH order may be supported on a first downlink carrier.

Before a wireless device initiates transmission of a random accesspreamble, it may access one or many of the following types ofinformation: a) available set(s) of PRACH resources for the transmissionof a random access preamble; b) group(s) of random access preambles andset(s) of available random access preambles in group(s); c) randomaccess response window size(s); d) power-ramping factor(s); e) maximumnumber(s) of preamble transmission(s); f) initial preamble power; g)preamble format based offset(s); h) contention resolution timer(s);and/or the like. These parameters may be updated from upper layers ormay be received from the base station before random access procedure(s)may be initiated.

According to some of the various aspects of embodiments, a wirelessdevice may select a random access preamble using available information.The preamble may be signaled by a base station or the preamble may berandomly selected by the wireless device. The wireless device maydetermine the next available subframe containing PRACH permitted byrestrictions given by the base station and the physical layer timingrequirements for TDD or FDD. Subframe timing and the timing oftransmitting the random access preamble may be determined based, atleast in part, on synchronization signals received from the base stationand/or the information received from the base station. The wirelessdevice may proceed to the transmission of the random access preamblewhen it has determined the timing. The random access preamble may betransmitted on a second plurality of subcarriers on the first uplinkcarrier.

According to some of the various aspects of embodiments, once a randomaccess preamble is transmitted, a wireless device may monitor the PDCCHof a first downlink carrier for random access response(s), in a randomaccess response window. There may be a pre-known identifier in PDCCHthat identifies a random access response. The wireless device may stopmonitoring for random access response(s) after successful reception of arandom access response containing random access preamble identifiersthat matches the transmitted random access preamble and/or a randomaccess response address to a wireless device identifier. A base stationrandom access response may include a time alignment command. Thewireless device may process the received time alignment command and mayadjust its uplink transmission timing according the time alignment valuein the command. For example, in a random access response, a timealignment command may be coded using 11 bits, where an amount of thetime alignment may be based on the value in the command. In an exampleembodiment, when an uplink transmission is required, the base stationmay provide the wireless device a grant for uplink transmission.

If no random access response is received within the random accessresponse window, and/or if none of the received random access responsescontains a random access preamble identifier corresponding to thetransmitted random access preamble, the random access response receptionmay be considered unsuccessful and the wireless device may, based on thebackoff parameter in the wireless device, select a random backoff timeand delay the subsequent random access transmission by the backoff time,and may retransmit another random access preamble.

According to some of the various aspects of embodiments, a wirelessdevice may transmit packets on an uplink carrier. Uplink packettransmission timing may be calculated in the wireless device using thetiming of synchronization signal(s) received in a downlink. Uponreception of a timing alignment command by the wireless device, thewireless device may adjust its uplink transmission timing. The timingalignment command may indicate the change of the uplink timing relativeto the current uplink timing. The uplink transmission timing for anuplink carrier may be determined using time alignment commands and/ordownlink reference signals.

According to some of the various aspects of embodiments, a timealignment command may indicate timing adjustment for transmission ofsignals on uplink carriers. For example, a time alignment command mayuse 6 bits. Adjustment of the uplink timing by a positive or a negativeamount indicates advancing or delaying the uplink transmission timing bya given amount respectively.

For a timing alignment command received on subframe n, the correspondingadjustment of the timing may be applied with some delay, for example, itmay be applied from the beginning of subframe n+6. When the wirelessdevice's uplink transmissions in subframe n and subframe n+1 areoverlapped due to the timing adjustment, the wireless device maytransmit complete subframe n and may not transmit the overlapped part ofsubframe n+1.

According to some of the various aspects of embodiments, a wirelessdevice may include a configurable timer (timeAlignmentTimer) that may beused to control how long the wireless device is considered uplink timealigned. When a timing alignment command MAC control element isreceived, the wireless device may apply the timing alignment command andstart or restart timeAlignmentTimer. The wireless device may not performany uplink transmission except the random access preamble transmissionwhen timeAlignmentTimer is not running or when it exceeds its limit. Thetime alignment command may substantially align frame and subframereception timing of a first uplink carrier and at least one additionaluplink carrier. According to some of the various aspects of embodiments,the time alignment command value range employed during a random accessprocess may be substantially larger than the time alignment commandvalue range during active data transmission. In an example embodiment,uplink transmission timing may be maintained on a per time alignmentgroup (carrier group) basis. Carrier(s) may be grouped in carriergroups, and carrier groups may have their own downlink timing reference,time alignment timer, and/or time alignment commands. Group(s) may havetheir own random access process. Time alignment commands may be directedto a time alignment group. The carrier group including the primary cellmay be called a primary carrier group and the carrier group notincluding the primary cell may be called a secondary carrier group.

According to some of the various aspects of embodiments, controlmessage(s) or control packet(s) may be scheduled for transmission in aphysical downlink shared channel (PDSCH) and/or physical uplink sharedchannel PUSCH. PDSCH and PUSCH may carry control and datamessage(s)/packet(s). Control message(s) and/or packet(s) may beprocessed before transmission. For example, the control message(s)and/or packet(s) may be fragmented or multiplexed before transmission. Acontrol message in an upper layer may be processed as a data packet inthe MAC or physical layer. For example, system information block(s) aswell as data traffic may be scheduled for transmission in PDSCH. Datapacket(s) may be encrypted packets.

In this specification, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” In this specification,the term “may” is to be interpreted as “may, for example,” In otherwords, the term “may” is indicative that the phrase following the term“may” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an isolatableelement that performs a defined function and has a defined interface toother elements. The modules described in this disclosure may beimplemented in hardware, software in combination with hardware,firmware, wetware (i.e hardware with a biological element) or acombination thereof, all of which are behaviorally equivalent. Forexample, modules may be implemented as a software routine written in acomputer language configured to be executed by a hardware machine (suchas C, C++, Fortran, Java, Basic, Matlab or the like) or amodeling/simulation program such as Simulink, Stateflow, GNU Octave, orLab VIEWMathScript. Additionally, it may be possible to implementmodules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. Finally, it needs to beemphasized that the above mentioned technologies are often used incombination to achieve the result of a functional module.

The disclosure of this patent document incorporates material which issubject to copyright protection. The copyright owner has no objection tothe facsimile reproduction by anyone of the patent document or thepatent disclosure, as it appears in the Patent and Trademark Officepatent file or records, for the limited purposes required by law, butotherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example, and notlimitation. It will be apparent to persons skilled in the relevantart(s) that various changes in form and detail can be made thereinwithout departing from the spirit and scope. In fact, after reading theabove description, it will be apparent to one skilled in the relevantart(s) how to implement alternative embodiments. Thus, the presentembodiments should not be limited by any of the above describedexemplary embodiments. In particular, it should be noted that, forexample purposes, the above explanation has focused on the example(s)using FDD communication systems. However, one skilled in the art willrecognize that embodiments of the invention may also be implemented inTDD communication systems. The disclosed methods and systems may beimplemented in wireless or wireline systems. The features of variousembodiments presented in this invention may be combined. One or manyfeatures (method or system) of one embodiment may be implemented inother embodiments. Only a limited number of example combinations areshown to indicate to one skilled in the art the possibility of featuresthat may be combined in various embodiments to create enhancedtransmission and reception systems and methods.

In addition, it should be understood that any figures which highlightthe functionality and advantages, are presented for example purposesonly. The disclosed architecture is sufficiently flexible andconfigurable, such that it may be utilized in ways other than thatshown. For example, the actions listed in any flowchart may bere-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable theU.S. Patent and Trademark Office and the public generally, andespecially the scientists, engineers and practitioners in the art whoare not familiar with patent or legal terms or phraseology, to determinequickly from a cursory inspection the nature and essence of thetechnical disclosure of the application. The Abstract of the Disclosureis not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include theexpress language “means for” or “step for” be interpreted under 35U.S.C. 112, paragraph 6. Claims that do not expressly include the phrase“means for” or “step for” are not to be interpreted under 35 U.S.C. 112,paragraph 6.

What is claimed is:
 1. A method comprising: a) transmitting, by a basestation configured to communicate employing a plurality of carriers, atleast one radio resource control message to a wireless device in aplurality of wireless devices, said at least one radio resource controlmessage: i) configured to cause in said wireless device: (1)configuration of at least one second carrier in said plurality ofcarriers; and (2) assignment of each of said at least one second carrierto a carrier group in a plurality of carrier groups, said plurality ofcarrier groups comprising: (a) a first carrier group comprising a firstsubset of said plurality of carriers, said first subset comprising afirst carrier, uplink transmissions by said wireless device in saidfirst carrier group employing a first synchronization signal transmittedon said first carrier; and (b) at least one second carrier group, asecond carrier group in said at least one second carrier groupcomprising a second subset of said at least one second carrier, saidsecond subset comprising a reference second carrier, uplinktransmissions in said second carrier group employing a secondsynchronization signal on said reference second carrier as a secondtiming reference; and ii) comprising a plurality of parameters specificto said wireless device, for each of said at least one second carrier:(1) if said plurality of parameters comprise a carrier group index forsaid second carrier, assigning said second carrier to one of said atleast one second carrier group identified by said carrier group index;and (2) otherwise, assigning said second carrier to said first carriergroup; b) transmitting, by said base station, a control commandconfigured to cause transmission of a random access preamble on randomaccess resources of a second carrier in said second carrier group; andc) transmitting, by said base station, a random access response on saidfirst carrier, said random access response comprising a timing alignmentcommand for said second carrier group.
 2. The method of claim 1, whereinsaid reference second carrier is an activated carrier in said secondcarrier group.
 3. The method of claim 1, wherein said first carriergroup is identified by a group index equal to zero.
 4. The method ofclaim 1, further comprising transmitting, by said base station, a timingalignment command to said wireless device, said timing alignment commandconfigured to cause substantial alignment of reception timing of uplinksignals in frames and subframes of a carrier group at said base station,said timing alignment command comprising an index identifying saidcarrier group.
 5. The method of claim 1, wherein said plurality ofparameters further comprise a time alignment timer parameter for eachcarrier group in said plurality of carrier groups.
 6. The method ofclaim 1, wherein said at least one radio resource control messageconfigured to further cause in said wireless device configuration of atime alignment timer for each of said plurality of carrier groups, saidtime alignment timer starting or restarting in response to said wirelessdevice receiving a timing alignment command to adjust uplinktransmission timing of a commanded carrier group in said plurality ofcarrier groups.
 7. The method of claim 1, further comprising receiving,by said base station, said random access preamble on said random accessresources, transmission timing of said random access preamble beingdetermined, at least in part, employing said second synchronizationsignal.
 8. The method of claim 7, further comprising transmitting, bysaid base station, at least one timing alignment command to saidwireless device, said timing alignment command comprising: a) a timeadjustment value; and b) an index identifying said second carrier group;and wherein said at least one timing alignment command is configured tocause substantial alignment of reception timing of said uplink signalsof said second carrier group at said base station.
 9. A base station,configured to communicate employing a plurality of carriers, comprising:a) one or more communication interfaces configured to communicate with awireless device via at least one wireless link; b) one or moreprocessors; and c) memory storing instructions that, when executed bysaid at least one or more processors, cause said base station to: i)transmit at least one radio resource control message to said wirelessdevice, said at least one radio resource control message: (1) configuredto cause in said wireless device: (a) configuration of at least onesecond carrier in said plurality of carriers; and (b) assignment of eachof said at least one second carrier to a carrier group in a plurality ofcarrier groups, said plurality of carrier groups comprising:  (i) afirst carrier group comprising a first subset of said plurality ofcarriers, said first subset comprising a first carrier; and  (ii) atleast one second carrier group, a second carrier group in said at leastone second carrier group comprising a second subset of said at least onesecond carrier; and (2) comprising a plurality of parameters, for eachof said at least one second carrier: (a) if said plurality of parameterscomprise a carrier group index for said second carrier, assigning saidsecond carrier to one of said at least one second carrier groupidentified by said carrier group index; and (b) otherwise, assigningsaid second carrier to said first carrier group; ii) transmit a controlcommand configured to cause transmission of a random access preamble onrandom access resources of a second carrier in said second carriergroup; and iii) transmit a random access response on said first carrier,said random access response comprising a timing alignment command forsaid second carrier group.
 10. The base station of claim 9, wherein saidplurality of parameters further comprise a time alignment timerparameter for each carrier group in said plurality of carrier groups.11. The base station of claim 9, wherein said at least one radioresource control message is configured to further cause in said wirelessdevice configuration of a time alignment timer for each of saidplurality of carrier groups, said time alignment timer starting orrestarting in response to said wireless device receiving a timingalignment command to adjust uplink transmission timing of a commandedcarrier group in said plurality of carrier groups.
 12. The base stationof claim 9, wherein said reference second carrier is an activatedcarrier in said second carrier group.
 13. The base station of claim 9,wherein said first carrier group is identified by a group index equal tozero.
 14. The base station of claim 9, wherein uplink transmissions bysaid wireless device in said first carrier group employ a firstsynchronization signal transmitted on said first carrier.
 15. A wirelessdevice comprising: a) one or more communication interfaces configured tocommunicate with a base station via at least one wireless link; b) oneor more processors; and c) memory storing instructions that, whenexecuted by said at least one or more processors, cause said wirelessdevice to: i) receive at least one radio resource control message fromsaid base station, said base station configured to communicate employinga plurality of carriers with said wireless device, said at least oneradio resource control message: (1) causing in said wireless device: (a)configuration of at least one second carrier in said plurality ofcarriers; and (b) assignment of each of said at least one second carrierto a carrier group in a plurality of carrier groups, said plurality ofcarrier groups comprising:  (i) a first carrier group comprising a firstsubset of said plurality of carriers, said first subset comprising afirst carrier; and  (ii) at least one second carrier group, a secondcarrier group in said at least one second carrier group comprising asecond subset of said at least one second carrier; and (2) comprising aplurality of parameters, for each of said at least one second carrier:(a) if said plurality of parameters comprise a carrier group index forsaid second carrier, assigning said second carrier to one of said atleast one second carrier group identified by said carrier group index;and (b) otherwise, assigning said second carrier to said first carriergroup; ii) receive a control command configured to cause transmission ofa random access preamble on random access resources of a second carrierin said second carrier group; and iii) receive a random access responseon said first carrier, said random access response comprising a timingalignment command for said second carrier group.
 16. The wireless deviceof claim 15, wherein said at least one radio resource control message isconfigured to further cause in said wireless device configuration of atime alignment timer for each of said plurality of carrier groups, saidtime alignment timer starting or restarting in response to said wirelessdevice receiving a timing alignment command to adjust uplinktransmission timing of a commanded carrier group in said plurality ofcarrier groups.
 17. The wireless device of claim 15, wherein saidplurality of parameters further comprise a time alignment timerparameter for each carrier group in said plurality of carrier groups.18. The wireless device of claim 15, wherein said instructions furthercause said wireless device to receive a timing alignment command fromsaid base station, said timing alignment command configured to causesubstantial alignment of reception timing of uplink signals in framesand subframes of a carrier group at said base station, said timingalignment command comprising an index identifying said carrier group.19. The wireless device of claim 15, wherein uplink transmissions bysaid wireless device in said first carrier group employing a firstsynchronization signal transmitted on said first carrier.
 20. Thewireless device of claim 15, wherein said second subset comprising areference second carrier, uplink transmissions in said second carriergroup employ a second synchronization signal on said reference secondcarrier as a second timing reference.